This invention relates to arrangements in which energy is absorbed by fold-back deformation of a deformable element.
As described in German Patent No. 12 82 363, fold-back deformation arrangements are used to slow down a motor vehicle in the event of, for example, a head-on collision, so as to prevent particularly critical deformations of the passenger compartment by providing a relatively gradual braking of the vehicle. In such fold-back deformation arrangements, kinetic energy is converted into deformation work by folding back at least one end of a deformation tube as it is forced against an appropriately shaped fold-back surface supported on a rigid stop.
A disadvantage of conventional fold-back deformation arrangements is that their components are not capable of angular motion with respect to each other in a common longitudinal plane. This shortcoming can be disadvantageous because deformation tubes only ensure selective deformation when the forces to be absorbed or converted to work are applied in the direction of the longitudinal axis of the deformation tube. When forces are directed obliquely thereto, on the other hand, there is a risk that the deformation tube will buckle, causing the deformation of the tube to have an undesirable force-displacement characteristic which first has a steep rise and then has a steep drop.